/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.el.lang;

import org.apache.el.util.ReflectionUtil;

import javax.el.FunctionMapper;
import java.io.Externalizable;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;

/**
 * @author Jacob Hookom [jacob@hookom.net]
 */
public class FunctionMapperImpl extends FunctionMapper implements
		Externalizable {

	private static final long serialVersionUID = 1L;

	protected Map<String, Function> functions = null;

	/*
	 * (non-Javadoc)
	 *
	 * @see javax.el.FunctionMapper#resolveFunction(java.lang.String,
	 *      java.lang.String)
	 */
	@Override
	public Method resolveFunction(String prefix, String localName) {
		if (this.functions != null) {
			Function f = this.functions.get(prefix + ":" + localName);
			return f.getMethod();
		}
		return null;
	}

	public void addFunction(String prefix, String localName, Method m) {
		if (this.functions == null) {
			this.functions = new HashMap<String, Function>();
		}
		Function f = new Function(prefix, localName, m);
		synchronized (this) {
			this.functions.put(prefix + ":" + localName, f);
		}
	}

	/*
	 * (non-Javadoc)
	 *
	 * @see java.io.Externalizable#writeExternal(java.io.ObjectOutput)
	 */
	@Override
	public void writeExternal(ObjectOutput out) throws IOException {
		out.writeObject(this.functions);
	}

	/*
	 * (non-Javadoc)
	 *
	 * @see java.io.Externalizable#readExternal(java.io.ObjectInput)
	 */
	@SuppressWarnings("unchecked")
	@Override
	public void readExternal(ObjectInput in) throws IOException,
			ClassNotFoundException {
		this.functions = (Map<String, Function>) in.readObject();
	}

	public static class Function implements Externalizable {

		protected transient Method m;
		protected String owner;
		protected String name;
		protected String[] types;
		protected String prefix;
		protected String localName;

		/**
		 *
		 */
		public Function(String prefix, String localName, Method m) {
			if (localName == null) {
				throw new NullPointerException("LocalName cannot be null");
			}
			if (m == null) {
				throw new NullPointerException("Method cannot be null");
			}
			this.prefix = prefix;
			this.localName = localName;
			this.m = m;
		}

		public Function() {
			// for serialization
		}

		/*
		 * (non-Javadoc)
		 *
		 * @see java.io.Externalizable#writeExternal(java.io.ObjectOutput)
		 */
		@Override
		public void writeExternal(ObjectOutput out) throws IOException {
			out.writeUTF((this.prefix != null) ? this.prefix : "");
			out.writeUTF(this.localName);
			// make sure m isn't null
			getMethod();
			out.writeUTF((this.owner != null) ?
					this.owner :
					this.m.getDeclaringClass().getName());
			out.writeUTF((this.name != null) ?
					this.name :
					this.m.getName());
			out.writeObject((this.types != null) ?
					this.types :
					ReflectionUtil.toTypeNameArray(this.m.getParameterTypes()));

		}

		/*
		 * (non-Javadoc)
		 *
		 * @see java.io.Externalizable#readExternal(java.io.ObjectInput)
		 */
		@Override
		public void readExternal(ObjectInput in) throws IOException,
				ClassNotFoundException {

			this.prefix = in.readUTF();
			if ("".equals(this.prefix)) this.prefix = null;
			this.localName = in.readUTF();
			this.owner = in.readUTF();
			this.name = in.readUTF();
			this.types = (String[]) in.readObject();
		}

		public Method getMethod() {
			if (this.m == null) {
				try {
					Class<?> t = ReflectionUtil.forName(this.owner);
					Class<?>[] p = ReflectionUtil.toTypeArray(this.types);
					this.m = t.getMethod(this.name, p);
				} catch (Exception e) {
					e.printStackTrace();
				}
			}
			return this.m;
		}

		/* (non-Javadoc)
		 * @see java.lang.Object#equals(java.lang.Object)
		 */
		@Override
		public boolean equals(Object obj) {
			if (obj instanceof Function) {
				return this.hashCode() == obj.hashCode();
			}
			return false;
		}

		/* (non-Javadoc)
		 * @see java.lang.Object#hashCode()
		 */
		@Override
		public int hashCode() {
			return (this.prefix + this.localName).hashCode();
		}
	}

}
